This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The principle objective is to compare the activity of phase I and II enzymes in xenobiotic metabolism in adolescents with or without non-alcoholic fatty liver disease. Specifically, we would compare CYP 1A2, CYP2D6, CYP3A, glucuronyl-transferase (UGT) and sulfono-transferase (ST) activity between these two populations. Other objectives include: To estimate caffeine clearance using a single plasma sample, and CYP 1A2 activity based on urine collection To determine the utility of saliva collection in determining absorption rate of caffeine and acetaminophen To determine the utility of saliva collection in determining acetaminophen metabolism